[mypyc] feat: extend stararg fastpath from #19629 with star2 fastpath

mypyc/irbuild/ll_builder.py

@@ -128,6 +128,8 @@
 from mypyc.primitives.bytes_ops import bytes_compare
 from mypyc.primitives.dict_ops import (
     dict_build_op,
+    dict_copy,
+    dict_copy_op,
     dict_new_op,
     dict_ssize_t_size_op,
     dict_update_in_display_op,
@@ -184,7 +186,12 @@
     str_ssize_t_size_op,
     unicode_compare,
 )
-from mypyc.primitives.tuple_ops import list_tuple_op, new_tuple_op, new_tuple_with_length_op
+from mypyc.primitives.tuple_ops import (
+    list_tuple_op,
+    new_tuple_op,
+    new_tuple_with_length_op,
+    sequence_tuple_op,
+)
 from mypyc.rt_subtype import is_runtime_subtype
 from mypyc.sametype import is_same_type
 from mypyc.subtype import is_subtype
@@ -788,23 +795,52 @@ def _construct_varargs(
 
         for value, kind, name in args:
             if kind == ARG_STAR:
+                # star args fastpath
                 if star_result is None:
-                    # fast path if star expr is a tuple:
-                    # we can pass the immutable tuple straight into the function call.
-                    if is_tuple_rprimitive(value.type):
-                        if len(args) == 1:
-                            # fn(*args)
-                            return value, self._create_dict([], [], line)
-                        elif len(args) == 2 and args[1][1] == ARG_STAR2:
-                            # fn(*args, **kwargs)
+                    if len(args) == 1:
+                        # fn(*args)
+                        if is_list_rprimitive(value.type):
+                            value = self.primitive_op(list_tuple_op, [value], line)
+                        elif not is_tuple_rprimitive(value.type):
+                            value = self.primitive_op(sequence_tuple_op, [value], line)
+                        # we can pass the immutable tuple straight into the function call.
+                        return value, self._create_dict([], [], line)
+                    elif len(args) == 2 and args[1][1] == ARG_STAR2:
+                        # fn(*args, **kwargs)
+                        # TODO: extend to cover(*args, **k, **w, **a, **r, **g, **s)
+                        if is_tuple_rprimitive(value.type):
                             star_result = value
-                            continue
+                        elif is_list_rprimitive(value.type):
+                            star_result = self.primitive_op(list_tuple_op, [value], line)
+                        else:
+                            star_result = self.primitive_op(sequence_tuple_op, [value], line)
+
+                        star2_arg = args[1]
+                        star2_value = star2_arg[0]
+                        if is_dict_rprimitive(star2_value.type):
+                            star2_fastpath_op = dict_copy_op
+                        else:
+                            star2_fastpath_op = dict_copy
+                        return star_result, self.primitive_op(
+                            star2_fastpath_op, [star2_value], line
+                        )
                         # elif ...: TODO extend this to optimize fn(*args, k=1, **kwargs) case
                     # TODO optimize this case using the length utils - currently in review
                     star_result = self.new_list_op(star_values, line)
                 self.primitive_op(list_extend_op, [star_result, value], line)
             elif kind == ARG_STAR2:
                 if star2_result is None:
+                    if len(args) == 1:
+                        # early exit with fastpath if the only arg is ARG_STAR2
+                        # TODO: can we maintain an empty tuple in memory and just reuse it again and again?
+                        if is_dict_rprimitive(value.type):
+                            star2_fastpath_op = dict_copy_op
+                        else:
+                            star2_fastpath_op = dict_copy
+                        return self.new_tuple([], line), self.primitive_op(
+                            star2_fastpath_op, [value], line
+                        )
+
                     star2_result = self._create_dict(star2_keys, star2_values, line)
 
                 self.call_c(dict_update_in_display_op, [star2_result, value], line=line)

mypyc/primitives/dict_ops.py

@@ -53,7 +53,7 @@
 )
 
 # Construct a dictionary from another dictionary.
-function_op(
+dict_copy_op = function_op(
     name="builtins.dict",
     arg_types=[dict_rprimitive],
     return_type=dict_rprimitive,

mypyc/primitives/tuple_ops.py

@@ -76,7 +76,7 @@
 )
 
 # Construct tuple from an arbitrary (iterable) object.
-function_op(
+sequence_tuple_op = function_op(
     name="builtins.tuple",
     arg_types=[object_rprimitive],
     return_type=tuple_rprimitive,